Water Management: Harvesting, Dams and Conservation

Seepage of rainwater into the ground helps recharge groundwater levels, which is a fundamental principle of water harvesting.

The water cycle is driven by phase changes like evaporation and condensation. Increasing the rates of these processes directly impacts the cycle's intensity and distribution.

Effective water harvesting requires a holistic approach, including reducing wastage, protecting water quality, and implementing better management practices.

Evaporation is the process of liquid water turning into vapor, which is directly accelerated by an increase in thermal energy (temperature).

The Sardar Sarovar Dam is a large-scale project on the Narmada River in India that has been the subject of significant controversy regarding environmental and social impacts.

A dam is a structure built across a river or stream to hold back water, creating a reservoir for various uses.

Efficient water harvesting provides multiple benefits, including increased water availability for irrigation, reduced waste, and mitigation of scarcity.

Rainwater harvesting reuse of water.
The term 'rainwater harvesting' refers to the collection of precipitation running off roof surfaces into cisterns or other storage vessels. Storm water reuse refers to the collection of runoff from catchment surfaces (e.g. roads, parking lots and landscaped areas).

Water harvesting systems provide versatile benefits, including recharging groundwater, providing water for irrigation, and supplying domestic needs.

Percentage of precipitation of rain that can be stored in dams of India is 10%. Dams are used as the reservoir of water for the agricultural, industrial and domestic use. Hydroelectric dams are used to generate electricity using hdropower.

While dams offer benefits like flood control and power generation, they often disrupt aquatic ecosystems and block the natural migration and spawning patterns of fish.

The Mullaperiyar dam is located in the Idukki district of Kerala. It is a masonry gravity dam on the Periyar River.

Large-scale projects, including dams, urban infrastructure, and transportation networks, often require land acquisition that leads to the displacement of local populations.

A major portion of water stored behind dams in the world is withdrawn for irrigation that is, evaporation and transpiration needs. Water used in excess of evaporation and transpiration needs appears in the system as surface or groundwater. The total quantum of flow and size and frequency of peak floods in the flood season reduce in the downstream due to a dam, reducing flood hazard due to inundation of land, crop and property. It also reduces congestion of run off in plains and coastal lands. Any soil erosion such as gullies already formed can be tackled by the construction of dams or obstructions. 

Large dams are frequently criticized for their negative social and environmental impacts, including blocking fish migration, increasing flood risks in certain areas, and displacing local communities.

The dam was built across Kaveri river in 1924. The kings laid the foundation for this project. It is the main source of water for Mysore districts. It has an ornamental garden attached to it.

Nagarjuna Sagar project was held in Nalgonda district of Telangana and Andhra Pradesh. The dam was built on the Krishna river. It is the largest and highest masonry dam in the world. 

Khadins, Ahars, and Kattas are traditional, indigenous water harvesting systems used in various parts of India to collect and store rainwater.

Check dams are small barriers built across gullies to slow down water flow, which helps in retaining water, reducing soil erosion, and facilitating groundwater recharge.

Raising dam heights increases the reservoir area, which leads to the submergence of land, resulting in the loss of flora, fauna, agricultural land, and the displacement of human and animal populations.